This application claims priority to German Application No. 10 2010 004 961.1-15 filed on Jan. 20, 2010.
The present disclosure relates to a power tool, particularly a power tool that is operated by hand, preferably a hammer drill.
A power tool such as a hammer drill usually includes a drive motor, a tool spindle to drive a tool in rotary manner, a rotary drive transmission to couple the drive motor to the tool spindle, a hammer mechanism to drive the tool in percussive manner, a hammer mechanism transmission to couple the drive motor to the hammer mechanism, and a switching device to activate and deactivate the hammer mechanism.
The disclosed power tool includes a switching device with a clutch that is integrated in the force path of the hammer mechanism transmission and has an actuation stroke for advancing and withdrawing, that is to say activating an deactivating, the hammer mechanism. The switching device is also designed so that a stroke direction of this actuation stroke extends perpendicularly to the axis of rotation of the tool spindle, or parallel to an axis of rotation of an element that is rotated manually to actuate the switching device. The actuation stroke may also extend perpendicularly to the axis of rotation of the tool spindle and parallel to the axis of rotation of the actuating element at the same time. In this case, the actuation stroke of the clutch corresponds to a linear displacement movement of a corresponding coupling member that causes the clutch to be advanced and withdrawn. Due to the orientation of the actuation stroke perpendicularly to the axis of rotation of the tool spindle and/or parallel to the axis of rotation of the actuating element as well as the integration of the clutch in the hammer mechanism transmission, the switching device is able to be located close to the tool spindle, thus enabling a construction of the power tool that is more compact overall.
According to one advantageous embodiment, the clutch may be integrated in the force path of the hammer mechanism transmission particularly easily if the hammer mechanism transmission is furnished on the input side with a driving gearwheel that is rotatable about an axis of rotation, and if the hammer mechanism transmission is furnished on the output side with a crank drive wheel that is supported so as to be rotatable about the axis of rotation of the driving gearwheel and which drives a connecting rod of the hammer mechanism when the hammer mechanism is activated. Inside the hammer mechanism transmission, the clutch includes a clutch ring arranged coaxially with the axis of rotation of the driving gearwheel, and on the crank drive wheel so as to be non-rotatable but axially displaceable on the crank drive wheel. Then, this clutch ring cooperates with the driving gearwheel to advance and withdraw the clutch in such manner that when the clutch ring is in the advanced state it transmits a torque from the driving gearwheel to the crank drive wheel, and when it is in the withdrawn state torque is not transmitted from the driving gearwheel to the crank drive wheel. The construction described here enables the clutch to be integrated in the hammer mechanism transmission in particularly compact manner.
According to a practical refinement of this arrangement, the driving gearwheel may include a slaving contour on the axial side facing the crank drive wheel, while a slaving contour corresponding to the slaving contour of the driving gearwheel is provided on the axial side of the clutch ring facing the driving gearwheel, and when the clutch ring is advanced this contour cooperates with the slaving contour on the driving gearwheel to transmit a torque, and when the clutch ring is withdrawn the slaving contour is axially separated therefrom. The axial slaving contours are capable of transmitting large torques and require only a small installation space.
A further refinement is then particularly practical, according to which the switching device has an actuating device for advancing and withdrawing the clutch, and which couples a manually operable actuating element with a displaceable coupling member of the clutch. It is expedient if the coupling member is the clutch ring. The actuating element, which is preferably arranged on the outside of a housing of the power tool, enables engagement with the hammer mechanism transmission, and thus with the clutch, so that it may be advanced and withdrawn.
The actuating device may preferably be equipped with a stroke element that is coupled to the clutch ring via at least one arm section extending parallel to the axis of rotation of the driving gearwheel, so that a stroke displacement of the stroke element away from and parallel to the axis of rotation of the driving gearwheel entrains the clutch ring, thereby extending it. In this way, the actuating device spans across crank drive wheel with the respective arm section of the stroke element to engage with the clutch ring. This enables the actuating device to be disposed coaxially with the axis of rotation of the driving gearwheel for a particularly economical arrangement in terms of space.
According to a further advantageous embodiment, in order to create a rotationally immovable and axially displaceable coupling between the clutch ring and the crank drive wheel, an axial section of the crank drive wheel may be equipped with an exterior slaving contour while the clutch ring is furnished with an interior slaving contour mating therewith, so that the clutch ring is arranged on the crank drive wheel via these slaving contours in non-rotating but axially displaceable manner with respect to the crank drive wheel. In this case, a particularly practical refinement may be realised if the slaving contours have polygonal profiles. These enable transmission of particularly large torques while causing low wear. The suggested design enables particularly compact construction with high functional reliability.
Further important features and advantages of the inventions are explained in the subordinate claims, the drawing, and the associated description of the figures with reference to the drawing.
Of course, the features described in the preceding and those that will be explained in the remainder of this document may be implemented not only in the combination cited in each case, but also in other combinations or alone without exceeding the scope of the present invention.
Preferred embodiments of the invention are illustrated in the figures and will be explained in greater detail in the following description, in which the same reference numbers are used to refer to identical, or similar, or functionally equivalent components.
In the drawing, all figures of which are schematic in nature,
As shown in
Housing 41 has a handle section 62 that extends parallel to motor housing 60 and which in the example is attached at the two opposite ends thereof, to spindle section 59 at one end and to motor section 60 at the other. Hammer drill 1 or the power tool may be connected to an external power supply via a cable 63 in handle section 62. In an alternative embodiment, hammer drill 1 may also be equipped with a rechargeable battery, so that it may be operated without connection to an electricity network.
As shown in
Switching device 7 is equipped with a clutch 9 that is integrated in the force path 10 of hammer mechanism transmission 6—indicated by a broken line. Clutch 9 has an actuating stroke 11, indicated by a double-headed arrow, which extends perpendicularly to axis of rotation 8 of tool spindle 3. Actuating stroke 11 is characterized by the direction of movement of a coupling member 12, in which coupling member 12 is displaceable in order to advance and withdraw clutch 9.
In the embodiments shown here, coupling member 12 is a clutch ring, which will also be designated with the number 12 in the following. This clutch ring 12 is arranged inside hammer mechanism transmission 6. In force path 10, clutch ring 12 is located between a driving gearwheel 13 of hammer mechanism transmission 6 on its input side and a crank drive wheel 14 of hammer mechanism transmission 6 on its output side. Driving gearwheel 13 engages with a drive sprocket 15 of a drive shaft 16 of drive motor 2. Driving gearwheel 13 is supported so as to be rotatable about an axis of rotation 17, which in the example extends parallel with an axis of rotation 18 which in the example extends parallel of drive shaft 16 of drive motor 2. At the same time, driving gearwheel 13 is supported in rotatable manner on a static shaft 19. Crank drive wheel 14 is also supported so as to be rotatable about the axis of rotation 17 of driving gearwheel 13. In the example, crank drive wheel 14 is also supported rotatably on static shaft 19. When hammer mechanism 5 is activated, crank drive wheel 4 drives a connecting rod 20 of hammer mechanism 5, driving a piston 21 in oscillating manner for example, which piston is supported inside the hollow tool spindle 3 so as to be displaceable in linear manner.
Clutch ring 12 is arranged on crank drive wheel 14 and coaxially with the axis of rotation 17 of driving gearwheel 13 in such manner that is axially displaceable on crank drive wheel 14 and at the same time coupled non-rotatably therewith. As illustrated in exemplary manner in the embodiment of
In the embodiment shown in
Besides crank drive wheel 14 and clutch ring 12, the section of clutch 9 illustrated in
The axial side of driving gearwheel 13 facing crank drive wheel 14 is furnished with a slaving contour 24. The axial side of clutch ring 12 facing driving gearwheel 13 is also furnished with a slaving contour 25 that is conformed in complementary manner to the slaving contour 24 on driving gearwheel 13. When clutch ring 12, and thus also clutch 9, is in the advanced state, the two slaving contours 24, 25 cooperate to transmit torque, and when clutch ring 12 is withdrawn they are no longer engaged with one another and no torque is transmitted. The one slaving contour 24 for example may be equipped with at least one pin, as shown in
In
In contrast to this,
In the embodiments shown here, switching device 7 is equipped with an actuation device 27. This includes a manually operable actuating element 28 and a stroke element 29. Actuation device 27 couples clutch ring 12 with actuating element 28 so that clutch 9, and thus also clutch ring 12, may be advanced and withdrawn. In this context, the movement is created via stroke element 29. The stroke element is furnished with at least one arm section 30, which extends parallel to the axis of rotation 17 of driving gearwheel 13. In the examples presented here, stroke element 29 is furnished with two such arm sections 30, which are arranged diametrically opposite one another with respect to axis of rotation 17 of driving gearwheel 13. In other words, the two arm sections 30 are disposed at an angle of 180° to one another. This means that they are arranged on opposite sides of axis of rotation 17 of driving gearwheel 13. Respective arm section 30 is coupled with clutch ring 12 in such manner that when stroke element 29 is moved away from driving gearwheel 13 in a stroke path extending parallel to axis of rotation 17 of driving gearwheel 13, it picks up and withdraws clutch ring 12, and advances the clutch ring when it moves in the opposite direction.
Stroke element 29 includes an annular section 31, from which the two arm sections 30 project, and which is aligned coaxially with axis of rotation 17 of driving gearwheel 13 and is located on a side of crank drive wheel 14 facing away from driving gearwheel 13. Arm sections 30 extend over the sides of crank drive wheel 14 and terminate close to clutch ring 12. In the example of
Actuating device 27 may be equipped with a stroke drive 36, as shown particularly in
Stroke drive 36 is equipped with a bushing 39, which is rotatable coaxially with annular section 31. This bushing 39 is furnished radially outwardly with at least one shoulder 40, which rises axially in the periopheral direction of bushing 39. In the example, one such shoulder 40 is provided on each sliding member 38. Accordingly, bushing 39 has three shoulders 40 arranged about the circumference thereof. Each shoulder cooperates with one of the sliding members 38 in such manner that a rotary displacement of bushing 39 is converted into a stroke displacement of stroke element 29. Stroke element 29 arranged so as to be rotationally immovable but stroke-displaceable in housing 41 or a housing compartment of hammer drill 1. When bushing 39 is rotated, sliding members 38 slide along the respective shoulder 40, causing a stroke displacement of stroke element 29. In order to protect the respective upper or lower end position of stroke element 29, the lower and/or upper end(s) of shoulders 40 may be equipped with a detent stage 42. When it reaches the respective end position, sliding member 38 engages with the associated detent stage 42 creating a haptically perceptible non-positive locking safety catch in the manner of a pressure point, and making it difficult or impossible for bushing 39 and thus also actuating element 28 to move on its own.
Actuating element 28 is connected in non-rotating manner with bushing 39. For example, a screw 43 is screwed from the inside through bushing 29 and into actuating element 28 for this purpose. Actuating element 28 is arranged on an external side of housing 41 of hammer drill 1. On the other hand, bushing 39 is arranged on an internal side of housing 41. A gasket 44 may be located between bushing 39 and housing 41 to seal housing 41 in the area of a passthrough 45. This gasket 44 is designed in such manner that it permits rotary movements of bushing 39. Bushing 39 may be furnished with a cylindrical extension 46 that protrudes through passthrough 45 from the inside to the outside of housing 41 to create a rotationally locked connection between actuating element 28 and bushing 39. Extension 46 has a plurality of radial gaps 47 that are engaged in positive locking manner by sections of actuating element 28. This is illustrated clearly in
Stroke element 29 is furnished with outwardly projecting longitudinal guides 48 in the area of its arm sections 30, in which guide elements 49 of housing 41 engage as shown in
As shown in
Rotary drive transmission 4 may expediently be a crown wheel 51 with axial spur gearing, and which also engages with drive sprocket 15 of drive motor 2 on the side diametrically opposite driving gearwheel 13. Crown wheel 51 is supported rotatably on tool spindle 3 and cooperates with a torque-dependent coupling 52. Torque-dependent coupling 52 includes a drive ring 53 that is arranged in rotationally fixed and axially displaceable manner on tool spindle 3 and is forced against crown wheel 51 with the aid of biasing spring 54. Coupling bodies 55 enable ring 53 and thus also tool spindle 3 to be driven. If the torque that is transmitted to tool spindle 3 from crown wheel 51 exceeds a predefined limit value, coupling bodies 55 displace ring 53 against the biasing force of spring 54 and crown wheel 51 is able to continue rotating when tool spindle 3 is stationary.
The foregoing description is only exemplary of the principles of the invention. Many modifications and variations are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than using the example embodiments which have been specifically described. For that reason the following claims should be studied to determine the true scope and content of this invention.
Number | Date | Country | Kind |
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102010004961.1-15 | Jan 2010 | DE | national |